A year ago whenever I'd request an SSD for review I'd usually get a 128GB drive built using 3x nm 4GB 2-bit MLC NAND die. These days the standard review capacity is twice that as most drives ship with 25nm NAND, using 8GB die. Seeing a bunch of scores for 240GB+ drives however is frustrating to all involved. At these capacities you're almost always looking at two die per NAND device, which has significant performance benefits due to interleaving. Most SSD controllers have eight NAND channels and with sixteen NAND deviecs with two die per device that's four NAND die that the controller can interleave access between for each channel. The 128GB drives by comparison halve the number of NAND, which only allows the controller to interleave requests among two die.
How read interleaving works on a single channel
Not only are these 240GB+ drives the best case performance you'd see from a particular SSD, they are also very expensive. At around $2/GB you're looking at over $500 for a high end 240GB+ SSD. I've spent the past few weeks gathering modern SSDs with 128GB of NAND on-board to provide a look at a more balanced point in the price/capacity spectrum.
| Mid-Range 2011 SSD Roundup | ||||||||
| Specs (6Gbps) | Corsair P3 128GB | Crucial RealSSD C300 128GB | Intel SSD 320 160GB | Intel SSD 510 120GB | OCZ Agility 3 120GB | OCZ Vertex 3 120GB | ||
| Controller | Marvell 6Gbps | Marvell 6Gbps | Intel 3Gbps | Marvell 6Gbps | SF-2281 | SF-2281 | ||
| Raw NAND Capacity | 128GB | 128GB | 176GB | 128GB | 128GB | 128GB | ||
| Spare Area | ~6.9% | ~6.9% | ~15.3% | ~12.7% | ~12.7% | ~12.7% | ||
| User Capacity | 119.2GB | 119.2GB | 149.0GB | 111.8GB | 111.8GB | 111.8GB | ||
| Number of NAND Devices | 8 | 16 | 12 | 16 | 16 | 16 | ||
| Number of die per Device | 4 | 2 | 1 - 2 | 2 | 1 | 1 | ||
| NAND Type | 32nm Toggle | 34nm ONFI 2.0 | 25nm ONFI 2.1 | 34nm ONFI 1.0 | 25nm ONFI 2.1 | 25nm ONFI 2.1 | ||
| Street Price | $229.99 | $234.99 | $304.99 | $284.49 | $242.04 | $252.99 | ||
| Cost Per GB | $1.797 | $1.836 | $1.906 | $2.222 | $1.891 | $1.976 | ||
Read on for our roundup of 120GB drives.
Source: http://www.anandtech.com/show/4421/the-2011-midrange-ssd-roundup
Kasey Chambers Megan Ewing Kristanna Loken Aubrey ODay Drew Barrymore
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